Background:This analysis was designed to
investigate prolactin levels in children and adolescents on
long-term risperidone treatment and explore any relationship with
side effects hypothetically attributable to prolactin (SHAP).

Method:Data from 5 clinical trials
(total N = 700) were pooled for this post hoc analysis. Children
and adolescents aged 5 to 15 years with subaverage intelligence
quotients and conduct or other disruptive behavior disorders
received risperidone treatment (0.02-0.06 mg/kg/day) for up to 55
weeks. Outcome measures analyzed included serum prolactin levels,
reported adverse events, and the conduct problem subscore of the
Nisonger Child Behavior Rating Form.

Results:Mean prolactin levels rose from
7.8 ng/mL at baseline to a peak of 29.4 ng/mL at weeks 4 to 7 of
active treatment, then progressively decreased to 16.1 ng/mL at
weeks 40 to 48 (N = 358) and 13.0 ng/mL at weeks 52 to 55 (N =
42). There was no relationship between prolactin levels and age.
Females returned to a mean value within the normal range (< =
30 ng/mL) by weeks 8 to 12, and males were close to normal values
(< = 18 ng/mL) by weeks 16 to 24. At least 1 SHAP was reported
by 13 (2.2%) of 592 children. There was no direct correlation
between prolactin elevation and SHAP.

Conclusion: With long-term risperidone treatment
in children and adolescents, serum prolactin levels tended to
rise and peak within the first 1 to 2 months and then steadily
decline to values within or very close to the normal range by 3
to 5 months.